River level monitoring based on multi-mission altimetry and spatio-temporal kriging – a case study in the Mekong river basin
Event: 2016 Ocean Surface Topography Science Team Meeting
Session: Science III: Two decades of continental water's survey from satellite altimetry - From nadir low-resolution mode to SAR altimetry, new perspectives for hydrology
Presentation type: Type Poster
We combine multi-mission altimetry data over the Mekong River using the geostatistical prediction method of ordinary spatio-temporal kriging based on covariances between the altimetry observations. We develop two different covariance models and evaluate their suitability for the Mekong River: a stationary and a non-stationary covariance model.
We use both models for combining altimetry measurements of Envisat, Jason-2, and SARAL. This way we achieve an improved temporal resolution of time series at any given location along the river. The method is validated against in-situ measurements at gauging stations along the Mekong as well as against close by altimeter measurements. Both covariance models yield satisfying results. The RMS values are for the stationary covariance model between 0.75 and 1.15 m and for the non-stationary between 0.62 and 0.74 m. The coefficients of determination are above 0.90 for both models at all validation sites. Furthermore, we show that spatio-temporal kriging is suitable to predict water states for periods with only sparse data coverage, i.e. in the data gap between the end of the Envisat in 2011 and the launch of the SARAL mission in 2013.